It's now unknown whether the hackers shared the public link to the materials with other media outlets, Game of Thrones fan sites, or additional television networks and/or executives. According to The Hollywood Reporter, the text in the video reads: "We successfully breached into your huge network.HBO was one of our hard targets to deal with but we succeeded (it took about 6 months)".

HBO said its forensic review of the incident is ongoing and noted that it believed further leaks were forthcoming.

On Monday, the network said it did not believe its email system in its entirety had been compromised.

It went on to say, "HBO spends 12 million for Market Research and 5 million for GOT7 advertisements".

The FBI is reportedly working with HBO to determine the extent of the data breach.

HBO is cooperating with cybersecurity firms and law enforcement to resolve the incident.

The note reportedly ended with an image of GoT villain the Night King with his arms raised, the word "standing" in one hand and "falling" in the other.

The Guardian reports the hackers have released 3.4 GB of proprietary data, including draft scripts of upcoming Game of Thrones episodes and a document containing phone numbers and email addresses for stars Peter Dinklage, Lena Headey and Emilia Clarke. While the original ransom amount was redacted from the letter, the hackers claim they earn between United States dollars 12 million and 15 million in a year, placing their ransom demands around USD 9-10 million.